​Doctor Crusher and the crew are part of a rescue mission in which they are able to save a severely injured Alien and bring him back to health, but his rapid healing suggests there's something else at work beyond the medical attention he's receiving. The Alien is unable to remember who he is so Beverly names him John Doe for the time being. We find out rather quickly that something is happening to John that's bigger than even he is aware and he is the first among his species to evolve. Lots of interesting concepts arise in this exciting episode.